«

Hi,

I work for a UK charity (We currently have three small offices where I
could not conceive of more than two VOIP 'lines' at each) we do also
have a lot of home based broadband enabled users.

I am currently experimenting with a single line Camrivox Flexor 151 /
Gradwell out over a Draytek Vigor 2800VG latest firmware QOS enabled
(Manual says when Qos enabled prioritises SIP by default) to Zen
Internet on a 256u/512down ADSL circuit and then on to Gradwell. The
Draytek/Zen/ADSL link is shared with typical Broadband applications
like surfing and email + the occasional bit of downloading. Voice
performance is 'not bad' but occasionally get 'words missing' which I
suppose could be network packet loss. Primarily the reason we are
interested in VOIP is to save money on Small Office to PSTN UK land-
line calls (Each office currently spends about £2k/year to BT 75% of
which is to UK PSTN national numbers!)

Anyhow we have just received a grant to spend on infrastructure and I
would like to 'spend some capital' to save ongoing running (Dreaded BT
phone bill! costs). How would you recommend I spend this money to
optimise our VOIP experience (and to minimise things such as packet
loss and other drop outs)

Should I (for example):

1/ Spend it on CISCO kit (to replace the Draytek's) - We may have
access to some refurbished but fully supported units?

2/ Change ISP to somebody who is 'best' at prioritising SIP traffic?
Who might that be?

3/ Upgrade the ADSL to MAX e.g. 512up/8M down or even ADSL2?

4/ Implement duplicate ADSL circuits (one for VOIP, one for everything
else?)

5/ Going for a more 'homogeneous' ISP environment (We currently use
plusNET, Zen and Daemon)

All of the above? none of the above? etc....

If you had a few thousand pounds to 'improve' your VOIP QOS (From
handset to UK PSTN national numbers) via infrastructure improvements,
where would you spend the money? What would be the priority as far as
QOS is concerend?

Many thanks,
Stef

wrote:
>
> 1/ Spend it on CISCO kit (to replace the Draytek's) - We may have
> access to some refurbished but fully supported units?

Then you have to spend $$$$ on a cisco expert to set it up for you.

> 2/ Change ISP to somebody who is 'best' at prioritising SIP traffic?
> Who might that be?

The ISP can't do anything about your upstream traffic, and this is what
is likely to cause you the most problems.


> 3/ Upgrade the ADSL to MAX e.g. 512up/8M down or even ADSL2?

Max will give more upstream. Sometimes it makes the line more unreliable

> 4/ Implement duplicate ADSL circuits (one for VOIP, one for everything
> else?)

Works nicely, but is operati


> 5/ Going for a more 'homogeneous' ISP environment (We currently use
> plusNET, Zen and Daemon)

Would maybe help a bit.


>
> If you had a few thousand pounds to 'improve' your VOIP QOS (From
> handset to UK PSTN national numbers) via infrastructure improvements,
> where would you spend the money? What would be the priority as far as
> QOS is concerend?
>

My favourite Qos product is the Converged Access CTX-1000. I may be
biased because the company I work for holds them in stock. But they
work really nicely.

They are a bridged mode device that you just slot in between your ADSL
router and your main network switch.

The other thing I would do is swap the the router for one that is based
on a AR7 chipset (such as the Zyxel P660R-61C) as these hold ADSL line
sync best on max lines.

I don't recommend any other Zyxel router for SIP traffic though.

The first thing to do is to graph the traffic throughput on your lines
(using some like MRTG, or cacti) and the latency/packet loss (using
smokeping). This will give an idea about your usage patterns and maybe
spot any faults on the lines.


Tim

In article <. com>,
<> wrote:
>Hi,
>
>I work for a UK charity (We currently have three small offices where I
>could not conceive of more than two VOIP 'lines' at each) we do also
>have a lot of home based broadband enabled users.
>
>I am currently experimenting with a single line Camrivox Flexor 151 /
>Gradwell out over a Draytek Vigor 2800VG latest firmware QOS enabled
>(Manual says when Qos enabled prioritises SIP by default) to Zen
>Internet on a 256u/512down ADSL circuit and then on to Gradwell. The
>Draytek/Zen/ADSL link is shared with typical Broadband applications
>like surfing and email + the occasional bit of downloading. Voice
>performance is 'not bad' but occasionally get 'words missing' which I
>suppose could be network packet loss. Primarily the reason we are
>interested in VOIP is to save money on Small Office to PSTN UK land-
>line calls (Each office currently spends about £2k/year to BT 75% of
>which is to UK PSTN national numbers!)
>
>Anyhow we have just received a grant to spend on infrastructure and I
>would like to 'spend some capital' to save ongoing running (Dreaded BT
>phone bill! costs). How would you recommend I spend this money to
>optimise our VOIP experience (and to minimise things such as packet
>loss and other drop outs)
>
>Should I (for example):
>
>1/ Spend it on CISCO kit (to replace the Draytek's) - We may have
>access to some refurbished but fully supported units?

You won't gain any "better" QoS.

>2/ Change ISP to somebody who is 'best' at prioritising SIP traffic?
>Who might that be?

If you find it, let me know

>3/ Upgrade the ADSL to MAX e.g. 512up/8M down or even ADSL2?

Definately.

>4/ Implement duplicate ADSL circuits (one for VOIP, one for everything
>else?)

Absolutely.

>5/ Going for a more 'homogeneous' ISP environment (We currently use
>plusNET, Zen and Daemon)

That will help if you do a lot of direct office to office connections
VPNs, etc. Your VoIP traffic is probably not going directly, but via a
Gradwell server, so it's less important.

>All of the above? none of the above? etc....

Upgrade to a Max service. That will give you more "headroom".

But do be aware that you can only efectively apply traffic shaping/QoS
to outbound traffic. There is nothing you can really do to inbound
traffic, because once it's been clocked over the wire, and arrived
at the router, it's too late for the router to do anything with it,
other than to pass it through. On the outboumd side, it can buffer up a
small amount of data and prioritise VoIP packets, (but it can only store
so much if it gets 160 byte VoIP packets and 1500 byte email packets,
you quickly run out of time if you store too many!) So QoS on a router
will do the right thing when you send a large email, upload big data,
etc. but will struggle to make any difference when someone downloads a
huge email/file/web page...

So a better solution is to get a completely separate 2nd BT line installed
and use it purely for VoIP. You don't even need QoS then. You might
even be able to front both routers with a 3rd router with 3 Ethernet
interfaces on to automagically work out the right circuit to put traffic
on, and fail-over to one line should the other go down - I've done this
with Linux routers, but don't know any commercial ones that can do this.

But either way, you're still at the mercy of the ISP that carries your
data (and really BT before it gets to the ISP), and whatever networks
are between your ISP and the telco. Telco (Gradwell) might be able to
tell you who they have the "best" peering with from that point of view,
so you can base your choice on that, but simply do a few traceroute
from each site on a different ISP to get a feel for it yourself.

>If you had a few thousand pounds to 'improve' your VOIP QOS (From
>handset to UK PSTN national numbers) via infrastructure improvements,
>where would you spend the money? What would be the priority as far as
>QOS is concerend?

A 2nd, dedicated ADSL line.

Gordon

Gordon Henderson <gordon+> wrote:
> But do be aware that you can only efectively apply traffic shaping/QoS
> to outbound traffic. There is nothing you can really do to inbound
> traffic, because once it's been clocked over the wire, and arrived
> at the router, it's too late for the router to do anything with it,
> other than to pass it through. On the outboumd side, it can buffer up a
> small amount of data and prioritise VoIP packets, (but it can only store
> so much if it gets 160 byte VoIP packets and 1500 byte email packets,
> you quickly run out of time if you store too many!) So QoS on a router
> will do the right thing when you send a large email, upload big data,
> etc. but will struggle to make any difference when someone downloads a
> huge email/file/web page...

I've heard that said before, and I don't quite understand. Most inbound
non-VOIP traffic is TCP. Why can't the router drop some packets in a TCP
stream, which will cause TCP windowing in the sender to think there's
network congestion and back off a bit? It won't help if you have lots of
short-lived TCP connections (webbrowsing lots of different sites) but if you
have a long TCP connection (downloading something) shouldn't the router be
able to persuade the sender to control the incoming bandwidth?

Theo

Theo Markettos wrote:
> I've heard that said before, and I don't quite understand. Most inbound
> non-VOIP traffic is TCP. Why can't the router drop some packets in a TCP
> stream, which will cause TCP windowing in the sender to think there's
> network congestion and back off a bit? It won't help if you have lots of
> short-lived TCP connections (webbrowsing lots of different sites) but if you
> have a long TCP connection (downloading something) shouldn't the router be
> able to persuade the sender to control the incoming bandwidth?
>

It can. And this technique works very well if done properly (a la CTX1000)

It takes a while for TCP connections to ramp up in speed. This gives a
qos box window to keep the inbound connection a bit suppresed and stop
it going too fast. A qos box has a few options, including sending ECN,
introducing latency to TCP connections or plain dropping packets.

Also in favour is the large download speed of ADSL - it takes a lot go
saturate the inbound connection.

Tim

On Aug 4, 7:05 pm, Tim <nutn...@kooky.org> wrote:
> relaxandchill...@gmail.com wrote:


> > 4/ Implement duplicate ADSL circuits (one for VOIP, one for everything
> > else?)
>
> Works nicely, but is operati

Looks like you were truncated! What were you planning to say...

My problem with having a duplicate BT line for a maximum of two voip
'circuits' is running cost (About £500/annum extra inc ISP costs).
What I wanted to do was to spend CAPITAL (from my grant) to offset
future running costs so I am quite interested in the CTX-1000
thinggy ... I may even set up a 'test rig' in one office first to try
it out:

Anyhow for first steps I think I'll:

1/ Get the Zen Internet ADSL circuit upgraded to 4xxK/up 8M/down or as
fast as it will go...

2/ May try downgrading the Camrivox Codex to GSM? as for PSTN some
people seem to say its 'good enough?'

Now currently I have a combo Vigor 2800VG as my ADSL termination and I
am also using it's PPTP VPN facilities for inbound 'dial-up' . If I
was to trial the CTX-1000 appliance would I have to replace the Vigor
and if so what ADSL termination/modem and router/firewall/VPNserver
would you suggest? My guess is that the CTX would sit between the ADSL
modem and new router/firewall/VPNserver... Or I may have got this
wrong?

(I am self taught with this Ethernet stuff AND STILL VERY MUCH
LEARNING! so any guidance would be appreciated)

Many thanks,
Stef

wrote:
> On Aug 4, 7:05 pm, Tim <nutn...@kooky.org> wrote:
>> relaxandchill...@gmail.com wrote:
>
>
>>> 4/ Implement duplicate ADSL circuits (one for VOIP, one for everything
>>> else?)
>> Works nicely, but is operati
>

.... operational expense, not capital expense.

> 1/ Get the Zen Internet ADSL circuit upgraded to 4xxK/up 8M/down or as
> fast as it will go...

Good idea. Makesure you have decent ADSL filters on your line first.
Preferably a BT style faceplate filter. Everything you can do to make
your line cleaner means you get better speeds and fewer resyncs on Max.



>
> 2/ May try downgrading the Camrivox Codex to GSM? as for PSTN some
> people seem to say its 'good enough?'

It is, but it isn't as nice to listen to.

Also, it is really unlikely (although not impossible) that you are
maxing out your bandwidth through voice calls alone.


>
> Now currently I have a combo Vigor 2800VG as my ADSL termination and I
> am also using it's PPTP VPN facilities for inbound 'dial-up' . If I
> was to trial the CTX-1000 appliance would I have to replace the Vigor
> and if so what ADSL termination/modem and router/firewall/VPNserver
> would you suggest? My guess is that the CTX would sit between the ADSL
> modem and new router/firewall/VPNserver... Or I may have got this
> wrong?

You could keep the vigor. Just you can't use its wireless bit or its
VoIP bit.

ADSL ---- Vigor ---- CTX-1000 ---- Ethernet switch

All your PCs, IP phones, wireless access point, whatever

The important thing is that any traffic that will go down the ADSL has
been through the CTX first.


Tim

On 4 Aug, 18:05, relaxandchill...@gmail.com wrote:

> Primarily the reason we are
> interested in VOIP is to save money on Small Office to PSTN UK land-
> line calls (Each office currently spends about £2k/year to BT 75% of
> which is to UK PSTN national numbers!)

VoIP probably isn't going to save much on calls to UK land lines
compared to other tariff options on your land lines.

You can use prefix dialling or Carrier Pre-Selection (CPS) to put your
calls through another carrier.

If you just want to save money on call charges I would focus on doing
that by paying less. Some of your capital could go on a least cost
routing box if needed.

Phil

On Aug 6, 9:33 am, PhilT <news...@gmail.com> wrote:

> VoIP probably isn't going to save much on calls to UK land lines
> compared to other tariff options on your land lines.

We currently have an ISDN/PBX through BT (Don't know who installed it
though). Call costs are extortionate though I understand we could
'move it from BT' to another (much cheaper) service provider?

Any suggestions for who to look at?
Any down sides to doing this?

>
> You can use prefix dialling or Carrier Pre-Selection (CPS) to put your
> calls through another carrier.
>
> If you just want to save money on call charges I would focus on doing
> that by paying less. Some of your capital could go on a least cost
> routing box if needed.

Doh? Have never come across these before...

Any suggestions?
How would they connect to our PBX?

To be honest, coming from an IT (not PBX) background I found the idea
of an ip/phone/dect/solution for two 'lines' to augment the existing
PBX seemed quite attractive. Now if I could move the PBX service to a
cheaper supplier that would be GR8 too!

------------------------

Also, two of our offices are moving to new premises soon so I suppose
we will need new PBX/phones... Any idea who we should be talking to
(We are in the charity sector) We have also used "Class Telecom" but
their fixed monthly charges seem high....

Could anyone point me to a good URL about how to purchase, and get
installed, a UK SME PBX + phones...

(Double DOH!!! last time I saw this being done, I was laying cat5
cables for the PC's whilst the "man from Class" was putting down cat5
for handsets?)

There must be a better way?

Who offers affordable converged solutions?

Thanks for all the help so far,
Stef

> Phil

wrote:

> On Aug 6, 9:33 am, PhilT <news...@gmail.com> wrote:

>> You can use prefix dialling or Carrier Pre-Selection (CPS) to put your
>> calls through another carrier.
>>
>> If you just want to save money on call charges I would focus on doing
>> that by paying less. Some of your capital could go on a least cost
>> routing box if needed.

Seconded - you have to spend a /hell/ of a lot on calls to justify a new
phone system from Cisco to 'save money'!

> Doh? Have never come across these before...
>
> Any suggestions?
> How would they connect to our PBX?

They don't - your order CPS through a service provider, then dial a short
code [4-5 digits] to route calls through them. Combining the cheapest
routes for each charge band and time of day is called 'least-cost routing'
or LCR.

> To be honest, coming from an IT (not PBX) background I found the idea
> of an ip/phone/dect/solution for two 'lines' to augment the existing
> PBX seemed quite attractive. Now if I could move the PBX service to a
> cheaper supplier that would be GR8 too!

How about 'yourself'? There are several PBX platforms that run on PC
hardware and use ethernet-connected handsets. Just think: you could expand
your empire and have a bigger budget next year!
But seriously, you could use a platform like Asterisk, to sit between your
existing PBX and your PSTN connection; this would bring you immediate
benefits [VoIP, LCR, potentially more economical handsets, softphones on
homeworkers laptops, fax2email] for relatively little outlay [multi-port
ISDN card + decent server to run it on + your time to set it up], whilst
not burning any bridges. You can keep your existing PBX, and migrate users
over to the new platform at your leisure. Most likely they'll be nagging
you to move them over when users of the new system tell them of all the
benefits, and that's the best way to have it when migrating people scared
of change.

> Also, two of our offices are moving to new premises soon so I suppose
> we will need new PBX/phones...

Define 'need'? Surely your PBX doesn't self-destruct when moved from one
place to another?

> Could anyone point me to a good URL about how to purchase, and get
> installed, a UK SME PBX + phones...
>
> (Double DOH!!! last time I saw this being done, I was laying cat5
> cables for the PC's whilst the "man from Class" was putting down cat5
> for handsets?)

Ever heard of structured cabling?

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